Truth is most often used to mean being in accord with fact or reality, or fidelity to an original or to a standard or ideal. Truth may also often be used in modern contexts to refer to an idea of "truth to self," or authenticity. The commonly understood opposite of truth is falsehood, which, correspondingly, can also take on a logical, factual, or ethical meaning. The concept of truth is discussed and debated in several contexts, including philosophy, art, and religion. Many human activities depend upon the concept, where its nature as a concept is assumed rather than being a subject of discussion; these include most (but not all) of the sciences, law, journalism, and everyday life. Some philosophers view the concept of truth as basic, and unable to be explained in any terms that are more easily understood than the concept of truth itself. Certainty is perfect knowledge that has total security from error, or the mental state of being without doubt. Objectively defined, certainty is total continuity and validity of all foundational inquiry, to the highest degree of precision. Something is certain only if no skepticism can occur. Philosophy (at least, historical Cartesian philosophy) seeks this state. It is widely held that certainty about the real world is a failed historical enterprise (that is, beyond deductive truths, tautology, etc.). This is in large part due to the power of David Hume's problem of induction. This book discusses the concepts of certainty, truth and to a certain extent, uncertainty and is designed to be a state of the art, superb academic reference work and provide an overview of the topic and give the reader a structured knowledge to familiarize yourself with the topic at the most affordable price possible. The accuracy and knowledge is of an international viewpoint as the edited articles represent the inputs of many knowledgeable individuals and some of the most current knowledge on the topic, based on the date of publication.